Appendix D: The Anybus State Machine
43 (48)
D.2
State Dependent Actions
The expected actions for each state are listed below.
State
Description
Expected Actions
SETUP
Anybus CompactCom Setup in progress.
NW_INIT
The Anybus CompactCom module is currently performing
network-related initialization tasks.
WAIT_PROCESS
The network Process Data channel is temporarily inactive.
The host application shall
regard the Read Process
Data as not valid.
IDLE
The network interface is idle. The exact interpretation of this
state is network specific. Depending on the configuration in
the offline action register, the Read Process Data may be either
updated or static (unchanged), unless “offline action” is set to
“clear”, in which case the Read Process Data is cleared in this
state.
The host application may
act upon the Read Process
Data, or go to an idle state.
PROCESS_ACTIVE
Normal data handling is possible
Perform normal data
handling.
ERROR
There is at least one serious network error.
EXCEPTION
The module has ceased all network participation due to a host
application related error.
This state is unrecoverable, i.e. the module must be restarted
in order to be able to exchange network data.
The host application must keep the Write Process Data updated in NW_INIT (initial data),
WAIT_PROCESS, IDLE, ERROR and PROCESS_ACTIVE since this data is buffered by the
Anybus CompactCom, and may be sent to the network after a state shift.
Anybus
®
CompactCom
™
B40 Modbus Serial User Manual
SCM-1202-130 1.1 en-US